If the electron falls from n = 3 to n = 2, in hydrogen atom then emitted energy is

The energy of electron in a shell is given as 

$$\begin{gathered} E=\frac{-13.6}{n^2}eV \\ {E}_3=\frac{-13.6}{3^2}=-1.5eV \\ {E}_2=\frac{-13.6}{2^2}=-3.4eV \\ {E}_3-E_2=(-1.5eV)-(-3.4eV)=1.9eV \end{gathered}$$